1. Field of the Invention
This invention relates to copolymers of ethylenechlorotrifluoroethylene and to solutions thereof.
2. Discussion of the Prior Art
Copolymers of ethylene and chlorotrifluoroethylene (CTFE) are known in the art. Copolymers (sometimes referred to as ECTFE copolymers) of ethylene and chlorotrifluoroethylene containing beween about 40 to 60 mol percent of ethylene units and correspondingly about 60 to 40 mol percent of chlorotrifluoroethylene units are disclosed, for example, in U.S. Pat. Nos. 3,947,525 to Robertson et al., 3,773,698 to Khattab and 3,745,145 to Khattab et al. ECTFE copolymers are also disclosed, for example, in U.S. Pat. No. 2,392,378 to Hanford, U.S. Pat. Nos. 3,371,076 and 3,501,446 to Ragazzini et al., British Patent No. 949,422, in European Polymer Journal, 1967, volume 3, pp. 129-144 and in Nucleonics, September 1964, pp. 72-74. ECTFE copolymers exhibit outstanding mechanical, electrical and chemical properties at high temperatures. For example, about equimolar ECTFE copolymers resist attack of most organic solvents at ambient as well as elevated temperatures, being only slightly soluble at 100.degree. to 150.degree. C. in 2,5-dichlorobenzotrifluoride/benzonitrile or o-dichlorobenzene mixtures of 10:90 to 50:50 volume ratio. They are also insoluble in bases and acids, including fuming nitric acid and possess high tensile strength and have melting points above about 200.degree. C. Such copolymers are suitable for making such useful articles as valves, gaskets, pipes, wire insulation, sheets and films.
Up to the present, however, such copolymers, being insoluble in the usual solvents, have been available only in powder or pellet form so that their utilization requires a thermal treatment of some kind in order to melt the copolymer. It would be desirable if there were provided ECTFE copolymers which were soluble in common solvents as well as solutions of such copolymers.